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Composite-ARF Extra 300L (2.12m/84")
techsupport@composite-arf.com
Glow Engine Installation
If fitting a 2-stroke or 4-stroke glow/methanol engine, for example OS140/160 or YS140/160,
you can generally use the same techniques as shown above for the DA-50 (gas engine) set-
up. Of course you will need to install either a solid F3A type 'beam' engine mount, or a 'Hyde'
mount - bolted onto the plywood firewall provided in the kit, installed as described above.
A glow motor will result in a very lightweight aircraft, but you will almost certainly need to install
all components, including the receiver batteries, as far forward as possible to achieve the cor-
rect Centre of Gravity. The Rudder servo mounting plate should also be installed as far forward
as possible, and you can save some weight in the tail by using hi-torque digital mini servos for
the elevators, of at least 7kg torque each.
The fuel tank base, made from the milled com-
posite-balsa parts included, can be used and
will accept a fuel tank up to 720ml if required.
You can also install the receiver on the vertical
bulkhead at the back of the tank base, as for
the gas engine (see photo)
The exhaust system, or mini-pipe, can still be
installed inside the composite exhaust tunnel -
but make sure that there is sufficient cooling as
described, and make a balsa baffle inside the
cowling if needed to direct cooling air over the
cylinder fins and prevent it just going out of the
air exit in the bottom of the cowl - without pass-
ing through the cylinder head cooling fins.
Cooling
Depending on your choice of motor and exhaust
system, mini-pipe or muffler you will need to
make provision for enough cooling to all these
components during flight. Make sure that the
area of the exit hole for the air to exit the exhaust
tunnel is at least 20% larger then the area of the
air inlet area.
Fuel Tank Base
Included in the kit are CNC milled plywood and
balsa/composite parts to make up a fuel-tank
base, which also incorporates a receiver mount
on the vertical back face. The photos show how
the parts are assembled, and the completed unit
is then glued on top of the fibreglass wing spar
tube in the centre of the fuselage with epoxy and
micro-balloons mix. Sand all the parts first,
assemble with thin CA - and then reinforce all
joints with a fillet of epoxy and micro-balloons
mixture.
Reinforce the joint where the vertical balsa sup-
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